The emux-synth driver has a possible AB/BA mutex deadlock at unloading the emu10k1 driver:

snd_emux_free() -> snd_emux_detach_seq(): mutex_lock(&emu->register_mutex) -> snd_seq_delete_kernel_client() -> snd_seq_free_client(): mutex_lock(&register_mutex)

snd_seq_release() -> snd_seq_free_client(): mutex_lock(&register_mutex) -> snd_seq_delete_all_ports() -> snd_emux_unuse(): mutex_lock(&emu->register_mutex)

Basically snd_emux_detach_seq() doesn't need a protection of emu->register_mutex as it's already being unregistered. So, we can get rid of this for avoiding the deadlock.

Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/synth/emux/emux_seq.c | 2 -- 1 file changed, 2 deletions(-)

diff --git a/sound/synth/emux/emux_seq.c b/sound/synth/emux/emux_seq.c index 7778b8e19782..188fda0effb0 100644 --- a/sound/synth/emux/emux_seq.c +++ b/sound/synth/emux/emux_seq.c @@ -124,12 +124,10 @@ snd_emux_detach_seq(struct snd_emux *emu) if (emu->voices) snd_emux_terminate_all(emu); - mutex_lock(&emu->register_mutex); if (emu->client >= 0) { snd_seq_delete_kernel_client(emu->client); emu->client = -1; } - mutex_unlock(&emu->register_mutex); }